Audio transducing apparatus and control circuits therefor



May 25, 1954 A. J. RUIZ 2,679,553 AUDIO TRANSDUCING APPARATUS AND CONTROL CIRCUITS THEREFOR Filed Sept. 22, 1950 IN V EN T QR. A Lfonso clEuw ww/lz Patented May 25, 1954 UNITED STATES PATENT OFFICE AUDIO TRANSDUCIN CONTROL CIRC G' APPARATUS AND UITS THEREFOR Alfonso J. Ruiz, Corpus Christi, Tex. Application September 22, 1950, Serial No. 186,299

14 Claims.

(01. (Granted under Title 35, U. S.

Code (1952),

sec. 266) electronic time control circuits especially adapted for automatic control of moving parts such, for example, as a motor commonly used in audio recording and reproducing apparatus.

Prior art devices for accomplishing the purcontrolling an electric circuit.

The Patent No. 2,411,501 to C. P. Brubaker, for Sound more than one recording and length with respect to time.

Other objects and advantages will become apparent after a consideration of the in connection with the accompanying drawings, in which:

Fig. 1 is a schematic electrical circuit diagram of the control tube arrangement according to a preferred embodiment of the invention; and

Fig. 2 is a schematic electrical circuit diagram of an audio recording system embodying the circult of Fig. l in slightly modified form.

Referring now to the drawings, in which like reference characters are used throughout to des- 17 a suitable dual triode tube, for example, one known in the trade as a type 6SN'7. The grid ll of the first triode section is connected to arm 2 of potentiometer 3 which is connected at one end thereof by way of capacitor 49 to lead 83. Lead 83 may supply an audio signal of any desired character. The other end of potentiometer 3 is connected to ground 4.

Connected to sistor network comprising The junction point 5 between aforementioned resistors I4 and I5 is connected to cathode l of tube 17, and is also connected to one terminal of The end terminal of rheostat i2 is connected by way of lead 2| and resistor It to the junction 20 between resistors l6 and I1. This junction 20 is also connected by and anode 8. shown, may be connected between junction 20 and ground. I

The cathode 22 of the second triode section of tube 1'! is connected to the junction l9 between aforementioned resistors l5 and I6. The anode ill of the second triode section of tube 17 is conconnected to lead and the other terminal and relay contact 84.

83 and relay contact H, thereof connected to lead Thus, armature relay 82 has an up position in contact with terminal 7i and a down position in contact with terminal 84;

In the above described circuit, as will be readily understood by those skilled in the art, component values may be suitably chosen to provide for operation substantially as follows:

Assuming switch t open, and the first triode section biased at or near cut-off, when an audio frequency voltage is fed to arm 2 through blocking condenser 49 to the first grid l l, the electrons released by cathode i are attracted to positive anode 8 and second grid 9.

This electron flow, also through resistor i2, causes anode B and grid 9 to assume a negative potential with respect to the second cathode 22. Capacitor 94, which is across resistors i2 and i3, is charged in a predetermined polarity, and it continues to hold grid 9 negative with respect to the second cathode 22 and point IQ for a few seconds after the audio frequency signal has ceased on grid ll. This time constant or period is variable with variable resistor l2; resistor 13 may be fixed for the least time response desired when there is no audio frequency voltage on grid Ii. After the audio signal has stopped and capacitor 94 discharged, plate or anode 8 and grid 9 thereupon assume a positive charge with respect to the second cathode and point it.

When this latter condition prevails there is an increased amount of electron flow through plate relay i2, thus it assumes a down position, closing contacts 82 and 84, which are provided for controlling exterior circuits.

When an audio frequency voltage is again fed into grid i 1, plate 8 and grid 9 assume a negative charge in respect to the second cathode 22 and junction point l9. through plate relay i2 is decreased, and the armature iii assumes an up position and makes contact with contact 'il. It is understood that biasing means, not shown, for example a spring, are provided for the relay.

The leads 86, 68, and 85 are provided for controlling exterior circuits, and switch 81 is provided for shorting selected ones of the paths through the relay contacts, when desired.

Switch ii is provided for manual operation of the relay, when desired.

Particular reference is made now to Fig. 2, in which a recording or other audio system utilizing the circuit of Fig. 1 is shown. At 39 is designated a pick-up, pick-up of the type used on aural disc recordings. This crystal pick-up feeds a minute alternating current voltage to the control grid 42 of voltage amplifier tube 78. Bias resistor 45 is provided, and shunt therewith is connected between grid 42 and ground 4. A higher potential alternating voltage drop will be developed from anode 4! across resistors 46 and 48. The voltage drops developed by resistor 46 will pass through coupling capacitor 51 to feed the control grid 53 of tube 19. The cathode of tube 19 is connected by way of resistor 55 and bypass capacitor 54 to ground. The voltage drops developed by resistor 48, will feed from junction point 41 through capacitor 49 and resistor is to level control potentiometer 3, and the delay circuit of tube '51 will be energized as aforedescribed, with the result that the relay having winding 12 is deenergized, and the circuit is closed through contacts 82 and II.

The anode 56 of tube 1-9 is connected to one terminal of the primary 6| of an output transformer, and is further connected by way of variable resistor 58 and capacitor 60 to ground 4.

for example, a crystal resistor 43 having capacitor 44 in Thus the electron flow The aforementioned primary 6! has the other terminal thereof connected to one terminal of filter capacitor 25, and to choke 59. Choke 59 is further connected as shown to filter capacitor ii, and the cathode of tube 74, which may be a type known in the trade as type 80. The plates 25] and 39 of tube F4 are connected to the end terminals of the high voltage secondary of a power transformer, which has the center tap thereof connected to ground. Filament windings iii and 32 are provided as shown, and it is understood supply power to the heater or filament elements of the tubes shown.

Primary 33 for the aforementioned power transformer is energized by way of fuse 65, switch 66, and leads '58 and 61, which it is understood are connected to a suitable source of A.-C. potential, not shown, for example, v., A.C., 60 cycles.

The energizing field 36 of motor 35 is also energized from the A.-C. source, by way of the contacts 82 and 1 l, or switch "ill in shunt therewith.

The reference numeral 34 represents a disc receiver. Member 38 is coupled by capacitor 31 to aforementioned terminal or relay contact 1| and consists of a metal plate so placed on the pick-up unit that, when the operators hand grasps this unit for placement, the hand touches the plate. The hand also touches companion metal plate l, placed on the pick-up unit and connected to arm 2 of potentiometer 3 and the attached grid H of tube 1?.

The output transformer includes secondary connecting to voice coil 63 of a speaker having cone 64, and which may include permanent field means, not shown, or choke 59 operatively associated therewith for generating a field.

As will now be apparent, when ones hand is applied to crystal pick-up 39 to initiate oper-. ation of the apparatus, plates I and 38 will be bridged by the hand and thereby a small voltage is fed from member 38 to member i and to the first grid ii of timing tube 11. This voltage 7 primes second grid 9 at a negative potential,

which capacitor 94 has the capacity ,to hold for a few seconds. This negative potential causes the plate relay to be deenergized, thereby permitting the relay biasing means to close the aural drive motor circuit through ll and 82. From thereon, crystal pick up 39 continues to supply the circuit with an alternating voltage, and keeps the electronic circuit relay in up position.

When this alternating voltage on arm 2 has come to a termination, capacitor 94 will discharge at its predetermined rate, determined by setting of plate variable resistor i2. At that time grid 9 will tend to assume a zero bias, and may tend to go positive, and permit plate relay 12 to open the motor electrical circuit through contacts 82 and H. It will be noticed that control 3 to the first grid is preferably so adusted as to have the lowest passages in the aural recording charge the capacitor to maximum. This will eliminate any difference in time factor, at the end of each aural recording.

Whereas the invention has been shown embodied in a sound reproducing system, it will be understood that a sound recording system could be used, if desired, pick up 39 being replaced by a microphone, for example, and loudspeaker 93-64 by a cutting arm.

The term ground as used herein is defined as acommon junction point or point of reference potential.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be by or for the government predetermined period after said A.-C. signal has ceased.

2. Control circuit apparatus comprising, in combination,

tube means to the positive terminal of said of potential, said voltage divider means and resister means being so proportioned that said relay means is deenergized While said A.-C. signal is applied to the grid of said first tube means, and for a predetermined period after said A.-C.

source signal has ceased.

3. Control circuit apparatus comprising, in

at a second predetermined positive potential with respect to ground, the anode of said first tube means being connected by a continuous electrical conductor to the grid of sam second tube means, resistor means having one end thereof directly viding an arrangement whereby said relay means is deenergized While said A.-C. signal is applied to the grid of said first tube means and for a predetermined period after said A.-C. signal has ceased.

4, Audio transducing apparatus comprising, in combination, audio transducer means, first and second electron discharge tube for applying an A,--C. signal from said transducer means to the grid of said first tube means, relay means having the winding thereof connecting the anode of said second tube means to said source of potential, and motor means opersignal is applied and for a predetermined period after said A.-C. signal has ceased.

5. Audio transducing apparatus comprising, in

the one of said taps, circuit means for applying an A.-C. signal from said transducer means between the grid ground, the cathode of said second tube means being connected to one of said taps, the anode of said first tube means being connected by a confirst tube means at .a tive potential with respect to ground, circuit 'otherend of said resistor means source of potential,

first predetermined 'posimeans for applying an :A.-C. signal from said transducer means between the grid of said first tube means and ground, second potential means for maintaining the cathode of said second tube means at a second predetermined positive potential with respect to ground, the anode of said first tube means being connected by a continuous electrical conductor to the grid of said second tube means, resistor means having one end thereof connected to said last named anode and grid, third potential means for maintaining the at a third positive potential with respect to ground, capacitor means connected in shunt with said resistor means, relay means having one terminal of the winding thereof connected to the anode of said second tube means, fourth potential means for maintaining the other terminal of the winding of said relay means at a fourth positive potential with respect to ground, said resistor means and first, second, third, and fourth potential means providing an arrangement whereby said relay means is deenergized while said A.C. signal is applied to the grid of said first tube means and for a predetermined period after said A.-C. sig nal has ceased, and motor means operativeiy connected to said relay means and controlled therefrom.

'7. In audio transducing apparatus, in combination, inductive pick-up means adapted to be energized when the hand of an operator is moved adjacent thereto, first and second electron discharge tube means each having a cathode, grid, and anode, the anode of said first tube means being connected by a continuous electrical conductor to the grid of said second tube means, a resistor means connecting said last-named anode and grid to said source of potential, capacitor means connected in shunt with said resistor means, means for applying an A.C. signal from said pick-up means to tie grid of said first tube means, relay means having the winding thereof connecting the anode of ,i

said second tube means to said source of potential, and motor means operatively connected to said relay means and controlled therefrom, said relay means causing the energization of said motor means while said A.C. signal is applied and for a predetermined period after said A.C. signal has ceased.

8. In audio transducing apparatus, in com-- bination, inductive picl -up means, first and second electron discharge tube means each having a cathode, grid, and anode, a source of potential having the negative terminal thereof connected to ground, voltage divider means having a plurality of spaced taps and connecting the positive terminal of said source to ground, the cathode of said first tube means being connected to the one of said taps, a priming circuit connected to said first tube grid having a permanent gap therein adapted to be electrically bridged when the hand of an operator is applied across the gap, circuit means for applying an A.-C. signal from said pick-up means between the grid of said first tube means and ground, the cathode of said second tube means being connected to one of said taps, the anode of said first tube means being connected by a continuous electrical conductor to the grid of said second tube means, variable resistor means connecting said last named anode and grid to one of said taps on said voltage divider means, capacitor means connected in shunt with said resistor means, relay means having the winding thereof connecting the anode of said second tube means to the positive terminal of said source of potential, said voltage divider means and resistor means being so proportioned that said relay means is deenergized while said A.C. signal is applied to the grid of said first tube means, and for a predetermined period after said A.- signal has ceased, and motor means operatively connected to said relay means and controlled therefrom.

9. In audio transducing apparatus, in combination, inductive pick-up means, first and second electron discharge tube means each having a cathode, grid, and anode, first potential means for maintaining the cathode of said first tube means at a first predetermined positive potential with respect to ground, a priming circuit connected to said first tube grid having a permanent gap therein adapted to be electrically bridged when the hand of an operator is applied across the gap, circuit means for applying an A.C. signal from said pick-up means between the grid of said first tube means and ground, second potential means for maintaining the cathode of said second tube means at a second predetermined positive potential with respect to ground, the anode of said first tube means being connected to the grid of said second tube means, resistor means having one end thereof connected by a continuous electrical conductor to said lastnamed anode and grid, third potential means for maintaining the other end of said resistor means at a third positive potential with respect to ground, capacitor means connected in shunt with said resistor means, relay means having one ternriinal of the winding thereof connected to the anode of said second tube means, fourth potential means for maintaining the other terminal of the winding of said relay means at a fourth positive potential with respect to ground, said resistor means and first, second, third, and fourth potential means providing an arrange ment whereby said relay means is deenergized while said A.C. signal is applied to the grid of said first tube means and for a predetermined period after said A.-C. signal has ceased, and motor means operatively connected to said relay mean and controlled therefrom.

10. Audio transducing apparatus of the character disclosed comprising, in combination, motor driven plate means for receiving a recording disc, audio transducer means operatively associated with said plate means, inductive pick-up means on said transducer means, first and second electron discharge tube means each having a cathode, grid, and anode, the anode of said first tube means being connected by a continuous electrical conductor to the grid of said second tube means, a source of potential, resistoi means connecting said last named anode anc grid to said source of potential, capacitor mean: connected in shunt with said resistor means, 1 priming circuit connected to said first tube gri having a permanent gap therein adapted to b electrically bridged when the hand of an operate is applied across the gap, means for applying a A.C. signal from said pick-up means and trans ducer means to the grid of said first tube mean and relay means having the winding there connecting the anode of said second tube meal to said source of potential, said motor drive plate means being operatively connected to sa relay means and controlled therefrom, said rel: means causing the energization of said mot means while said A.-C. signal is applied and for a predetermined period after said A.-C. signal has ceased.

11. Audio transducing apparatus of the character disclosed comprising, in combination, motor driven plate means for receiving a recording disc, audio transducer means operatively asso being so proportioned that said relay means is deenergized while said A.-C. signal is applied to the grid of said first tube means-and for a predetermined period after said A.-C. signal has controlled therefrom.

12. Audio transducing apparatus of the character disclosed comprising, in combination, mo-

therein adapted to be electrically bridged when the hand of an operator is applied across the gap, circuit means for applying an A.-C. signal ill 10 tial means for maintaining the other end of said resistor means at a third positive shunt with said resistor having one terminal of the nected to the anode of said second tube means, fourth potential means for maintaining the other terminal of the Winding of said relay means at a fourth positive potential with respect to ground,

sald resistor means and first, second, third, and

energized While said A.-C. signal is being applied and said tube means being enclosed in a single container.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,004,893 Hall June 11, 1935 2,214,482 Schmidt Sept. 10, 1940 2,288,000 Kelly June 30, 1942 2,368,477 Kinsman Jan. 30, 1945 2,561,602 Valentino et al July 24, 1951 2,574,618 Cade Nov. 13, 1951 

